Salusbury, Thomas Mathematical collections and translations 1667
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380
and sport with our Fancies) hath, I say, hath permitted that the

motions for every other respect, except to resolve the ebbing and
flowing of the Sea, assigned long since to the earth, should be found
now at last to answer exactly to the cause thereof; and, as it

were, with mutual a emulation, the said ebbing and flowing
to appear in confirmation of the Terrestrial motion: the judices
whereof have hitherto been taken from the cœlestial Phænomena,
in regard that of those things that happen on Earth, not any one
was of force to prove one opinion more than another, as we al­
ready have at large proved, by shewing that all the terrene occur­
rences upon which the stability of the Earth and mobility of the
Sun and Firmament is commonly inferred, are to seem to us per­
formed in the same manner, though we supposed the mobility of
the Earth, and the immobility of them. The Element of Wa­
ter onely, as being most vast, and which is not annexed and con­
catenated to the Terrestrial Globe as all its other solid parts are;
yea, rather which by reason of its fluidity remaineth apart sui
juris, and free, is to be ranked amongst those sublunary things,
from which we may collect some hinte and intimation of what the
Earth doth in relation to motion and rest. After I had many
and many a time examined with my self the effects and accidents,
partly seen and partly understood from others, thar are to be ob­
served in the motions of waters: and moreover read and heard
the great vanities produced by many, as the causes of those acci­
dents, I have been induced upon no slight reasons to omit these

two conclusions (having made withal the necessary presuppo­
sals) that in case the terrestrial Globe be immoveable, the flux
and reflux of the Sea cannot be natural; and that, in case those
motions be conferred upon the said Globe, which have been long
since assigned to it, it is necessary that the Sea be subject to eb­
bing and flowing, according to all that which we observe to hap­
pen in the same.

Nature in sport
maketh the ebbing
and flowing of the
Sea, to approve the
Earths mobility.

The tide, and
mobility of the
Earth mutually
confirm each other

All terrene ef­
fects, indifferently
confirm the motion
or rest of the
Earth, except the
ebbing and flowing
of the Sea.

The first gene­
ral conclusion of
the impossibility of
the ebbing and
flowing the immo­
bility of the terre­
strial Globe being
granted.

SAGR. The Proposition is very considerable, as well for it
self as for what followeth upon the same by way of consequence,
so that I shall the more intensly hearken to the explanation and
confirmation of it.

The knowledge
of the offests con­
tributes to the in­
vestigation of the
causes.

SALV. Because in natural questions, of which number this
which we have in hand is one, the knowledge of the effects is a
means to guide us to the investigation and discovery of the cau­
ses, and without which we should walk in the dark, nay with
more uncertainty, for that we know not whither we would go,
whereas the blind, at least, know where they desire to arrive; there­
fore first of all it is necessary to know the effects whereof we en­
quire the causes: of which effects you, Sagredus, ought more
abundantly and more certainly to be informed than I am,